1. Field
Embodiments relate to a secondary battery.
2. Description of the Related Art
Generally, unlike a primary battery which is not rechargeable, a secondary battery is capable of being charged and discharged. A low-capacity secondary battery composed of a single battery cell may be used as a power source for various small portable electronic devices, e.g., cellular phones and camcorders. A high-capacity secondary battery in which a plurality of battery cells are connected to each other in a pack structure may be used as a power source for, e.g., driving a motor of a hybrid electric vehicle.
Secondary batteries may be manufactured in various shapes. Generally, secondary batteries may be classified as, e.g., a cylindrical shape battery or a prismatic shape battery. The secondary battery is formed such that an electrode assembly formed by disposing a separator as an insulator between positive and negative electrode plates and an electrolyte are accommodated in a case. A cap assembly having electrode terminals may then be provided on the case. The electrode terminals may be connected to the electrode assembly and may be externally exposed through the cap plate.
Here, gaps may exist between the electrode terminals and the cap plate, and an electrolyte may infiltrate or leak out through the gaps. When the electrolyte infiltrates through gaps between the electrode terminal and the cap plate, an electrical short circuit may occur between the electrode terminal and the cap plate, rapidly deteriorating the battery and reducing battery capacity. Also, when such leakage occurs through a gap between a cap plate and electrode to the outside, the leaked electrolyte may corrode various structures outside of or adjacent to the battery. In addition, moisture from the outside may enter a case through the gaps. Such an unfavorable phenomenon may be aggravated in a case of a secondary battery employed in an electric device that repeatedly vibrates, such as an electric vehicle or an electric drill.